Powering Fuel Cells with Wastewater

As companies and facility managers are increasingly recognizing the benefits of monetizing wastewater, two Virginia Tech researchers say they have found a way to maximize the amount of electricity that can be generated from the wastewater that would otherwise be flushed down the toilet.

In an article published in Scientific Reports, Xueyang Feng and Jason He traced bacteria, which led them to discover that the working relationship between two specific substrates produced more energy than either did separately. This work could help in the development of new treatment system called a microbial fuel cell, the researchers say.

“Tracing the bacteria gave us a major piece of the puzzle to start generating electricity in a sustainable way,” said Feng, an assistant professor of biological systems engineering. “This is a step toward the growing trend to make wastewater treatment centers self-sustaining in the energy they use.”

The team found that when the two substrates — lactate and formate — are combined, the output of energy is far greater than when they are working separately. The organics work in tandem with receptors in fuel cells.

The results of this work encouraged the further development of microbial fuel cells, especially system scaling up. The He lab is currently operating a 200-L microbial fuel cell system in a local wastewater treatment plant for evaluating its long term performance with actual wastes.

At IWS’ largest residential installation to date, the 172-unit Sail condos by Adera Development Corp. at the University British Columbia, its SHARC system (SHARC stands for sewage heat recovery) provides hot water for all of the units at about 550 percent efficiency. This saves residents about 70 percent on their hot water heating bills. It also reduces emissions by about 100 metric tons per year, IWS says.